Abstract: The bitrate of a digital signal is adapted in a dynamic way to the bandwidth available on a transmission channel, through the operations of: converting the digital signal into a multiple-description format, so as to have available a plurality of descriptions of the digital signal; and transmitting on the transmission channel descriptions of the digital signal chosen from among said plurality of multiple descriptions, the number of the transmitted descriptions being determined as a function of the bandwidth available on the transmission channel.

Abstract: A motion estimator operating on a recursive mode reduces the number of operations per pixels required by the particular coding process being implemented. The coding process includes the MPEG standard. A method is based on the correlation existing among motion vectors associated to macroblocks in a common position in temporally adjacent images. The method is also associated to macroblocks belonging to the same picture and spatially adjacent to the current macroblock being processed. By using this double correlation, the calculation burden is reduced.

Abstract: Relaying on a temporal correlation among successive pictures and using a hierarchical recursive motion estimation algorithm, the hardware complexity of video coders complying with the MPEG-2 standard can be significantly reduced without an appreciable loss of quality of the video images being transferred. Relaying on a temporal correlation among successive pictures is also performed on a spatial correlation of motion vectors of macroblocks of the currently processed picture.